To explore the effects of high temperature and aquaporins inhibitor (HgCl2) treatments on the expression of aquaporins genes in flag leaves, the relative water content in panicle and flag leaves, and the development of rice endosperm, the ‘over-expression OsPIN1a’ rice was treated with 38 ℃ /33 ℃ and 0.1 mmol/L HgCl2 for 6 days during the flowering period. The main physiological parameters including relative water content, seed setting rate, 1 000-grains weight, endosperm cell structure, and expression of tonoplast intrinsic proteins (OsTIPs) and plasma membrane intrinsic proteins (OsPIPs) in ears or flag leaves were measured. Results showed that, compared to optimal temperature (30 ℃/28 ℃) treatment, high temperature or HgCl2 stress significantly decreased contents of relative water, seed setting rate and 1 000-grain weight, activities of mitochondrial in pollen and stigma, pollen number in stigma, and expressions of OsTIPs and OsPIPs family genes. Moreover, starch accumulation in endosperm cells was delayed and irregular shape of its granules was observed. High temperature combined with HgCl2 stress induced more severe development inhibition and toxicity. In conclusion, lower expression of OsTIPs and OsPIPs family genes could aggravate the growth and the development inhibition induced by high temperature, and decreased the activity of pollen and stigmas, resulting in lower seed setting rate and poor grain filling.